Being born either too early or too late may have a long-term effect on children’s academic performance, finds a new study. This study detailed the relationship between gestational age at birth and school grades at age 16 across the full range of pregnancy duration (22 to 45 completed weeks), by weight-for-gestational age, focusing on extremely pre- and post-term births and taking into account possible effects within and between families. Grade averages were lower for pre- and post-term children than for term-counterparts, and were lowest in children showing evidence of poor foetal growth, irrespective of gestational age, suggested the study published in the International Journal of Epidemiology.

Grades of pre- and post-term children remained lower than those of term counterparts when considering spontaneous deliveries, uncomplicated unassisted deliveries, children with normal Apgar, or without congenital anomalies. However, induced post-term deliveries were not associated with reduced school performance. Among matched siblings, within-family effects were weaker, particularly in the preterm sibling cohort and less so in post-term children. Irrespective of gestational age at birth, there was an independent effect of foetal growth restriction on later school performance which has persisted over time.

There may be shared familial traits which influence risk of birth at non-optimal gestational age and also affect the academic performance of those born early or late. These may include modifiable risk factors such as poor maternal diet, smoking during pregnancy, and maternal obesity. “Less favourable outcomes of post-term infants with poor foetal growth suggest that placental insufficiency may become particularly toxic to neurodevelopment the longer a pregnancy endures,” said Hein Heuvelman, researcher at the University of Manchester.